Used the ISO expansion feature of my Canon 40D last night to image M-13 at a 3200 ISO "equivalent" (whatever that means?). Took a series of unguided 33 second subs through my 80mm Stellarvue Nighthawk II mounted on a CG-5, and stacked with five darks and three flats in DSS. Some processing with PS CS3. Some noise as expected with the expanded ISO feature.
